Structure–properties relationship in RE3−xMgxNi9H10–13 (RE = La,Pr,Nd) hydrides for energy storage
Structure–properties relationship in RE3−xMgxNi9H10–13 (RE = La,Pr,Nd) hydrides for energy storage
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DOI：
10.1016/j.jallcom.2014.12.091
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发表时间：
2015-10
影响因子：
6.2
通讯作者：
V. Yartys;R. Denys
中科院分区：
文献类型：
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作者：
V. Yartys;R. Denys
三元RE3−xmgxni9金属间化合物是很有前途的电池电极材料。对（La,Pr,Nd）3−xmgxni9h10 - 13氢化物和初始金属间化合物的结构-性质关系的研究表明：(a)镁含量的增加导致所有稀土金属的三角晶胞（a,c，V）逐渐缩小，Mg在REMg2Ni9中的溶解度达到最高；(b)当镁的含量从x= 1.0增加到1.1 ~ 1.2，并由Pr和Nd取代La时，解吸压力在0.01 ~ 20 bar H2的大范围内变化，热力学稳定性显著降低；(c)中子粉末衍射表明，在remgni4和reni5层中，D原子的分布几乎相等；(d)由mgh6八面体和nih4四面体构成的h亚晶格内发生局部氢有序，显示出定向的金属-氢键。Mg对RE的部分取代使得（La,Pr,Nd）3−xmgxni9氢化物的电化学放电容量比商用ab5型电极大25%，达到400 mA h/g。通过选择合适的合成路线、初始混合物中Mg的含量以及均质过程的时间和温度，合成具有高度均匀性的材料是很重要的。
Ternary RE3−xMgxNi9intermetallics are promising battery electrode materials. Studies of the structure–properties relationships in the (La,Pr,Nd)3−xMgxNi9H10–13hydrides and initial intermetallics revealed the following: (a) Increase of magnesium content causes a gradual shrinking of the trigonal unit cells (a,c,V) for all studied RE metals, with the highest solubility range of Mg reached in REMg2Ni9; (b) Significant lowering of the thermodynamic stability follows an increase in magnesium content fromx= 1.0 to 1.1–1.2 and a replacement of La by Pr and Nd, with desorption pressures changing in a broad range, from 0.01 bar to 20 bar H2; (c) Neutron powder diffraction shows a nearly equal distribution of D atoms within the REMgNi4and RENi5layers; (d) Local hydrogen ordering occurs within the H-sublattice built from MgH6octahedra and NiH4tetrahedra displaying a directional metal–hydrogen bonding. A partial substitution of Mg for RE allows the electrochemical discharge capacity of the (La,Pr,Nd)3−xMgxNi9hydrides to become 25% greater than that of the commercial AB5-type electrodes, reaching 400 mA h/g. Synthesis of the materials with a high degree of homogeneity is important and has been achieved by choosing an appropriate synthesis route, content of Mg in the initial mixtures, and time and temperature of the homogenisation process.